1152 infection control & hospital epidemiology october 2017, vol. 38, no. 10
table 4. Bacterial Acquisition and Transmission Eventsa During 120 Shifts in the ASCOT Trial Organism
Total (N=120), No. (%)
Nurse clothing contamination event Any
MRSA MSSA VRE
E. coli Klebsiella spp.
Acinetobacter spp. Pseudomonas spp.
Environmental contamination event Any
MRSA MSSA VRE
E. coli Klebsiella spp.
Acinetobacter spp. Pseudomonas spp.
Acq
19 (16) 12 (10) 6 (15) 4 (3) 7 (6) 1 (1)
Trans 3 (3)
3 (3) 1 (1)
1 (1) 3 (3) 1 (1)
3 (3) 2 (2)
2 (5) 0 0
00 0 2 (2) 4 (3) 1 (1) Acq
20 (17) 11 (9) 4 (3) 4 (3) 3 (3)
Trans 2 (2)
1 (1) 3 (3) 0
2 (5) 1 (3) 1 (3) Acq
9 (23) 2 (5) 1 (3) 2 (5)
00 0 1 (1) 6 (5) 0
1 (1) 3 (8) 0
Control (N=40), No. (%)
Acq
Trans 4 (10) 1 (3) 0 0 0
1 (3) 1 (3) 1 (3) Trans 6 (15) 1 (3) 1 (3) 1 (3) 0
1 (1) 2 (5) 0
Scrub 1 (N=40), No. (%)b
Acq
7 (18) 2 (5)
4 (10) 0 0 0
1 (3) 0
Acq
5 (13) 1 (3) 2 (5) 0 0 0
1 (3) 0
Trans 3 (8) 2 (5) 1 (3) 0 0 0 0 0
Trans 2 (5) 1 (3) 1 (3) 0 0 0 0 0
Scrub 2 (n=40), No. (%)c
Acq
6 (15) 0
3 (8) 1 (3) 0 0
2 (5) 0
Acq
6 (15) 1 (3) 1 (3) 1 (3) 0 0
2 (5) 0
NOTE. Acq, acquisition; MSSA, methicillin-susceptible S. aureus, MRSA, methicillin-resistant S. aureus; Trans, transmission; VRE,
vancomycin-resistant enterococci. aAn “acquisition event” was defined as contamination identified at the end of the shift that was not present at the beginning of the shift. A “transmission event” was defined as an acquisition event for which the source of contamination was identified and confirmed from another
member of the transmission triangle. A nurse or the environment could have more than 1acquisition or transmission event during each shift. bScrubs contained a complex element compound with embedded silver-alloy. cScrubs impregnated with an organosilane-based quaternary ammonium and a hydrophobic fluoroacrylate copolymer emulsion.
figure 1. Description of 23 confirmed transmission events in the “transmission triangle” during the ASCOT study.
the HCP (P<.01), but no significant differences were detected in the amount of VRE or gram-negative bacilli contamination. In contrast, 3 previously published prospective randomized trials failed to show significant decreases in bacterial con- tamination in nurses or ambulance personnel.13–15 Our methods helped provide a more complete analysis of
this technology, as we measured and adjusted for environ- mental contamination and included important organisms such as MSSA and vancomycin-susceptible Enterococcus in our analyses. In light of these methodological advantages and the weight of the studies summarized above, we conclude that antimicrobial-impregnated scrubs are not efficacious at decreasing the bacterial burden on HCP during a single shift. We hypothesize that the lack of efficacy in this setting is related
to the low-level disinfectant capabilities of the textiles coupled with repeated inoculation events and a short time frame (eg, a shift of 8 to 12 hours) in which to have an effect. Antimicrobial-impregnated textiles may be more effective in settings with potentially prolonged exposure and activity, including curtains and linens.11,18 Our study confirmed that HCP clothing regularly becomes contaminated with important pathogens6,19,20 and, as a result, can act as a source for transmission. For example, in a cohort study of 57 nurses, approximately half of the nurses’ surgical scrubs became contaminated with VRE, MRSA, and/or C. difficile by the end of a standard shift.21 Similarly, HCP clothing contaminated with S. aureus, Acinetobacter spp., and/or enterococci is associated with increased risk of contaminated HCP hands.22 Indeed, HCP clothing can become contaminated by interacting with either patients or the environment.23 Patients regularly contaminate their environment,24,25 which
may be the biggest predictor of HCP contamination. Morgan et al23 analyzed microbiological data from 585 HCP–patient interactions and concluded that positive environmental cultures led to a 4-fold increase in the risk ofHCP contamination. In our study, the patient was the source of contamination for all organisms encountered in the environment. Nurses acquired important pathogens during 19% of shifts; we confirmed the source of transmission during 10% of shifts. Importantly, the
Trans
5 (13) 0
2 (5) 1 (3) 0 0
2 (5) 0
Trans 3 (8) 0
1 (3) 1 (3) 0 0
1 (3) 0
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